A player that is out becomes transparent

[TheoPannetier]

A player that has been killed should be made aware of it, appearing as transparent, at least on its own screen (see #608).

  {
    // (609) A player that is out becomes transparent
    player p;
    assert(p.get_color().get_opaqueness() == 255);
    p.die();
    assert(p.get_color().get_opaqueness() == 100);
  }

[Luxwor]

solved the issue